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Has anyone had issues with the 02 sensors hitting the engine? The guy installing mine called and said he cant mount them because the outlet for the sensors are right on the engine. Mine came with 4 02 sensor outlets and im almost 99% sure they're the right headers judging by the pictures from the other ebay header thread. Don't know what to do now..

you can only use the lower two holes. so the "postcat" holes in each sensor, butr the o2 sensors need to be in the headers before the headers are bolted in.

Well either way if i can only use the lower 2 thats fine but he told me he can't even mount them because the pre 02 sensor outlets are hitting the engine. I have to swing by tomorrow to actually look at it but thats just what he told me right now. Didn't say anything about if he can put it on without using those outlets, just said he cant mount them.

Well either way if i can only use the lower 2 thats fine but he told me he can't even mount them because the pre 02 sensor outlets are hitting the engine. I have to swing by tomorrow to actually look at it but thats just what he told me right now. Didn't say anything about if he can put it on without using those outlets, just said he cant mount them.

they should be no where near the engine at all. That doesnt make sense. I think he is doing something wrong. One should push into the body slightly and the other should mount freely facing out.

Alright well i'll take a look tomorrow. So to clarify something.. I thought you could use all 4 sensors with the 2 pre cats going in normally but the post cats need the defouler, but now from what you said, the pre cats arent used at all and i'm assuming then must be relocated to the drugbin?

Alright well i'll take a look tomorrow. So to clarify something.. I thought you could use all 4 sensors with the 2 pre cats going in normally but the post cats need the defouler, but now from what you said, the pre cats arent used at all and i'm assuming then must be relocated to the drugbin?

I have an insane test tomorrow but I HIGHLY suggest you re-read the OP.

defoulers dont work. you can only fit all 4 if you use Anthony@bimmerbrake headers. you can relocate the two precats to drug bin and sim the post cats.

WHat?! You CANNOT relocate the precats. They determine many things relating to combustion and feed the info back to the ECU and tell it to adjust accordingly. You can only put the post-cats in the drugbin and sim them. The pre-cat sims are there for a reason. If you remove them from the exhaust stream then there WILL be consequences.

Basically: put the pre-cat SENSORS in the post-cat BUNGS ON THE HEADERS and plug/block the pre-cat bungs on the headers. Put the post-cat SENSORS in the drugbin and then SIM THE POST-CAT SENSORS.

If you need proof, read the first post of this thread. Do not skim. Read his explanation of what happens when a pre-cat O2 sensor dies (same as relocation).

WHat?! You CANNOT relocate the precats. They determine many things relating to combustion and feed the info back to the ECU and tell it to adjust accordingly. You can only put the post-cats in the drugbin and sim them. The pre-cat sims are there for a reason. If you remove them from the exhaust stream then there WILL be consequences.

Basically: put the pre-cat SENSORS in the post-cat BUNGS ON THE HEADERS and plug/block the pre-cat bungs on the headers. Put the post-cat SENSORS in the drugbin and then SIM THE POST-CAT SENSORS.

If you need proof, read the first post of this thread. Do not skim. Read his explanation of what happens when a pre-cat O2 sensor dies (same as relocation).

Ok so here's my question, the last time I checked, and I'm pretty sure it's this way, my post cat o2 sensors are wired and in mu dung bin...the pre cat o2's are in the headers...so I have o2 sims but havnt connected them yet but soon will however I have heard from different people that o2 sims won't really do anything....

Here is the full story: me and my friends put headers in the car...some how the pre cat ones ended up in the dung bin and post cat sensors were in the headers...car ran lean, bad mpg, loss of power....so switched the pre and post sensors around...car ran lean, bad mpg, loss of low end power....but then randomly my car started to run rich, bad mpg, loss of power....turns out my Maf was bad and crankshaft position sensor was bad....got It fixed....get car back and it's running lean again but car is stalling out at high speeds when in neutral....mech tells me it's Ccv so I replace it and VCG at the same time....now my question is: I heard from one member that headers will only cause catalytic inefficiency codes, no lean or rich codes, but Another fanatic told me it will run lean and catalytic inefficiency codes will appear....I'm putting my o2 sims in tomorrow, but will that resolve my running lean issue? ( btw i have yet to get a catalytic inefficiency code)

sounds like you got the o2 sensors backwards. this means that the o2 sensors that go to the headers should plug in on the left(if standing at front of car) side of the engine. the ones that plug in on top are post cats.

the other issue is that the precats have to be in the right order - your car is sensing the wrong order - so what you need to do assuming you have the right ones plugged in in the first place, is switch them. just unplug and replug should take all of 30 seconds on the sie of the motor. This is detailed in teh original post

Quote:

7. OMGZZZZZ my engine is loping and throwing miss fire codes and crap and I dont know what to do.....!!!!!!!!

It will be ok. This is normal. All you did was mix up the precat o2 sensors. basically you put two o2 sensors into the headers. right? and you plugged them into the harness on the left side of the engine. right? Simply go and unplug both of them, and swap the connectors. Problem solved.